1. Field of the Invention
The present invention relates to a lubrication device of four-stroke-cycle engine.
2. Discussion of the Background
An engine equipped to the vehicle, such as a motorcycle, has many sliding and rotating parts inside. Therefore, lubricating oil is supplied to every part inside the engine by using a lubrication device in order to decrease frictional resistance of every part by the function of lubricating all so that the engine functions sufficiently. Further, there is a kind of engine wherein every part of the engine is cooled actively by lubricating oil.
The typical example of the lubricating device for a four-stroke-cycle engine with a wet sump type lubricating system is as follows:
An oil pan is disposed at the lower part of an engine case of an engine. An oil pump pumps up the lubricating oil stored in the oil pan. The oil is then filtered with an oil filter, and cooled by an oil cooler in some cases. After the filtration (and cooling), the oil is sent to the parts inside the engine, where the lubrication is required, through a main gallery that is formed inside the engine case.
Further, in most cases, the oil passage that reaches to the main gallery from the oil pump is formed normal to the mounting surface of the oil filter because of a mold construction of the engine case.
However, because of the construction of the engine such as arrangements of the oil pump, the oil filter and the oil cooler, many connecting passages may be needed in order to form the oil passage network. As a result, the time increase in processing the engine case and the requirements of many blind plugs for the connecting passages would become the factors for the cost increasing.
Furthermore, similar to the oil passage, the connecting passages are arranged normal to each other because of the mold construction of the engine case, which make the oil passages longer. Moreover, since the connecting passages are arranged normal to each other, there might be a chance that the oil pressure in the passages would drop. This unnecessary drop of the oil pressure would lead undesirable factors, such as an unnecessary enlargement of the oil pump, restrictions of layouts, weight increases, and an increase of the mechanical loss.
An object of the present invention is to substantially eliminate defects or drawbacks encountered in the prior art described above and to provide a lubrication device of four-stroke-cycle engine that simplifies and reduces the length of the oil passage that reach to the main gallery from the oil pump.
This and other objects can be achieved according to the present invention by providing a lubrication device of four-stroke-cycle engine comprising an engine case dividable at least into two pieces in vertical direction in a normal operating situation, the divided engine case having matching surfaces being obliquely upward to the rear, a lower part of the engine case having substantially horizontal bottom surface portion, an oil pan attached to the bottom surface portion, oil passages, which guide lubricating oil in the oil pan to a main gallery by an oil pump, formed in the lower part of the engine case, and an oil filter disposed on the oil passages, the lubrication device comprising:
a front surface portion of the lower part of the engine case formed normal to matching surfaces of the lower part of the engine case and the oil pan,
an oil-filter-mounting-base formed onto the front surface portion of the lower part of the engine case,
an oil passage, which extends to an oil entrance of the oil filter from the oil pump, formed in parallel with the matching surfaces of the divided engine case, and
an additional oil passage, which connects an oil exit of the oil filter and the main gallery.
In preferred embodiments, the lubrication device further comprising:
an oil cooler disposed on the oil passages, and
an oil-cooler-mounting-base formed with the oil-filter-mounting-base onto the front surface portion of the lower part of the engine case side by side in the engine width direction,
wherein the oil passage comprises a first oil passage, and the additional oil passage is composed of a second oil passage and a third oil passage,
the second oil passage being connected to an oil exit of the oil filter and an oil entrance of the oil cooler, is formed normal to the front surface portion of the lower part of the engine case, and in parallel with the matching surfaces of the lower part of the engine case and the oil pan, and
the third oil passage, being extended to the main gallery from an oil exit of the oil cooler, is formed in parallel with the matching surfaces of the divided engine case.
Further, an oil entrance port and an oil exit port for the oil filter are disposed in the oil-filter-mounting-base coaxially, and an oil entrance port and an oil exit port for the oil cooler are disposed in the oil-cooler-mounting-base coaxially, the oil exit port for the oil filter and the oil entrance port for the oil cooler, being connected to the second oil passage which is formed normal to the front surface portion of the lower part of the engine case, are disposed in centers of the mounting-bases, the oil entrance port for the oil filter, being connected to the first oil passage, is disposed in the circumference side of the oil exit port for the oil filter, and the oil exit port for the oil cooler, being connected to the third oil passage, is disposed in the circumference side of the oil entrance port for the oil filter.
Furthermore, the oil entrance port for the oil filter and the oil exit port for the oil cooler, being connected to the first and third oil passages, are disposed separately in vertical direction.
Further, the second oil passage is composed of two sub-passages which connect the oil exit port for the oil filter and the oil entrance port for the oil cooler to a main passage, while the main passage is disposed behind the mounting-bases and below the first oil passage.
Moreover, the oil-filter-mounting-base and the oil pump are disposed on the same side of the engine.
According to the lubrication device of the present invention of the characters described above, arranging the passages without interfering with each other, and in a shortest distance, becomes possible. Moreover, the oil passages become simplified, which leads to a reduced cost of processing the engine case.
Further, the mutual interference of each passage may be avoided, so that the unnecessary drop of the oil pressure would be prevented. As a result, an unnecessary enlargement of the oil pump, restrictions of layouts, weight increases, and an increase of the mechanical loss are prevented.
The further nature and features of the present invention will be made clearer hereunder through descriptions with reference to the accompanying drawings.